What are the cheat codes for Resident Evil 3: Nemesis? I googled first but all I get are hints e.g., how to beat Nemesis, how to solve certain puzzles etc. Is there any cheat codes which will allow me to get powerful weapons or infinite ammo?

I've found this link which specifies some sort of codes to be applied to a save game file, but I don't have any clue how to do it......

In reference to the link that you have added: What you are seeing on that website would be Hex Editing saved game files to give you items or change things around. It is much easier to hex edit saved game files with the PC version of the game than the PS version. The two versions share the same gamesave file format, but it would require much more effort to move a game save between your Playstation and a PC.